Friction bodies which contain reinforcing fibers, lubricants, abrasives, inorganic materials and fillers in a binder matrix cured under the action of heat and pressure are widely used in various technical fields, in particular as brake pads, clutch pads, or friction pads. These friction bodies generally comprise a support, or a support plate, made of metal or synthetic material and at least one friction pad disposed thereon. The joining of the friction pad and the support is usually accomplished by riveting or bonding. The metallic support may be present in the form of a plate or hub with inner or outer teeth, or, however, also in the form of a brake block support.
The friction pad normally is produced by molding the corresponding friction materials under heat and stamping or cutting. The so produced friction pad is then bonded with the use of an adhesive, or riveted, onto the support which may consist of metal or an injection-molded synthetic material. The adhesives employed for this purpose contain solvents and are cured in the oven at elevated temperatures, thereby releasing solvents. The also employed two-component adhesives do not possess the heat resistance required in the use of the friction bodies.
Joining the friction pads to the support by riveting is laborious and expensive and only offers a pointwise fixing of the friction pad, so that the latter may bulge between the “rivets”. Another large drawback lies in the high cost of manufacture of the metal supports, especially when these supports have inner or outer teeth which must have a very high fitting accuracy. Last, problems arise from the different thermal expansion of the metallic support and the friction pad due to distortion of the friction pads and their becoming detached from the support.
DE 21 09 907 A, for instance, discloses a pad for vehicle brakes, in particular a brake block consisting of a plurality of parts having different qualities, which parts are integrally joined, in particular by bonding with an adhesive. The joining of these individual parts to one another, and to the required support consisting, for example, of steel, not only is expensive due to providing this metallic support and the required adhesive but also cannot be satisfactory in view of the requisite joining of the parts of the friction body to one another and to the support.
From DE 39 05 627 C2 there is known a method of manufacturing a brake body for a disc brake comprising a flat back plate and as a friction pad a lining on the back plate, with at least two lining portions with different friction properties. The method resides in charging the granular material which corresponds to the different lining portions and which may contain different portions of polishing material depending on the respective lining portions into a molding frame comprising a partitioning unit separating the individual lining portions and at the same time forming all of the lining portions on the back plate by a pressing treatment and subjecting the lining portions on the back plate to a heating treatment under pressure.
EP 0 859 164 A1 discloses a friction element, in particular for an automobile brake or a friction clutch, wherein the friction element has a pad support and a friction pad mounted thereon, said friction pad having a variable friction value μ depending on the degree of wear so as to prevent in this manner the occurrence of undesired noises during operation.
The friction bodies known from this state of the art which comprise a support and at least one friction pad disposed thereon cannot be satisfactory in so far as the friction pad and the support are manufactured separately and in a manner involving high cost and must subsequently be joined, for example by bonding with an adhesive or by riveting, which methods of attachment often do not offer the strength that is required in practice, so that there may occur deformation, or possibly even detachment, of the friction pad disposed on the support.